[proxy] - USers should be able to update partition

[Malini Kamalambal]

The proxy API currently allows only create, read, list & delete partitions.
The API needs to include an UPDATE partition as well
Users should be able to update partitions, i.e. add /remove hosts, change weights etc.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/48737

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/49262

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/49262
Committed: http://github.com/openstack/marconi/commit/99aaa0272c1c0761606367d3afa201f4256241af
Submitter: Jenkins
Branch: master

commit 99aaa0272c1c0761606367d3afa201f4256241af
Author: Alejandro Cabrera <email address hidden>
Date: Fri Sep 27 15:54:05 2013 -0400

    feat (proxy/admin): allow partition modifications

    This patchset adds one new method to the partitions API
    - PATCH /v1/partitions/{partition}

    The partitions storage layer is also updated to support a simpler
    update interface:
    - update(self, name, **kwargs) [with kwargs in ('hosts', 'weight')]

    The partitions transport layer is cleared of cruft and reuses JSON
    handling utilities from the queues transport layer.

    This patch implementation uses jsonschema to achieve self-documenting,
    strict format validation of the incoming input.

    The partition storage controllers are modified accordingly, as are the
    tests. More tests are added for the partitions transport layer to
    verify the correctness and to ease future refactorings.

    Change-Id: Ifa92b1225421196f95131c2b74e3c07b07c4cfd4
    Implements: blueprint placement-service
    Closes-Bug: 1230841